Petroleum lubricants stabilized with nitroesters



United States PETROLEUM LUBRICANTS STABILIZED WITH NITROESTERS Edward 0. Bennett, Houston, Tex., assignor to Commercial Solvents Corporation, Terre Haute, Ind, a corporation of Maryland No Drawing. Filed June 27, 1958, Ser. No. 744,918

3 Claims. (Cl. 252-515) My invention relates to a stablized petroleum lubricant and more particularly to a process for the production of stablized petroleum lubricants containing as the active where R is selected from the group consisting of phenyl, methyl, ethyl and propyl; R is selected from the group consisting of hydrogen, methyl, ethyl and'propyl; R is selected from the group consisting of hydrogen, methyl, ethyl and propyl.

It is well known that organisms from the groups consisting of Corynebacterium, Achromobacter, Pseudomonas, Nocardia and Mycobacterium metabolize petroleum hydrocarbons and fatty acids and thereby produce undesirable oxidation products.

The petroleum industry has long been interested in the stabiliziation of various petroleum products such as cutting oils, hydraulic fluids, etc., against break-down by bacteria which metabolize 'the hydrocarbons with the concurrent formation of deleterious metabolites.

Many compounds have been used as stabilization agents in lubricants, but very few have been found to be commercially successful due to the fact that the compounds are unstable, or are not active against a wide variety of microorganisms.

Among the compounds included within the scope of my invention are 2-nitro-3-pentylacetate, 3-nitro-4-hexylpropionate, 2-nitro-l-butylbenzoate, 3 nitro 4 pentylbutyrate, 2-nitro-1-ethylacetate, 2-nitro-3-butylacetate, 2- nitro-l-propylacetate, etc. I have found that in some instances I can obtain total inhibition of bacterial growth in petroleum lubricants at concentrations as low as 100 parts per million. I prefer to include at least 1000 parts per million in most petroleum formulations. However, I can employ amounts up to 2% by weight of the active nitroesters when the latter is soluble to this ex tent in the particular petroleum hydrocarbon composition.

I have found that my active ingredients are effective bacteriostatic agents in petroleum containing lubricants such as cutting oil, penetrating oils, grinding lubricants, iron tinning lubricants, core oils, hydraulic fluids, etc.

The following examples set out lubricating compositions in which my active ingredients act as effective bacteriostatic agents. It is not intended that my invention be limited to the compositions, portions, or lubricants set out below, but rather I intend for all the equivalents and variations obvious to those skilled in the art to be included within the. scope of this specification and the attached claims.

Example I My active ingredients were tested in a 25:1 watercutting oil emulsion. The cutting oil concentrate used atent O ice was a proprietary cutting oil containing no bacterial inhibitors sold by the Texas Company under the trade name Soluble Oil TL -3337. Five ml. portions of the watercutting oil emulsion were placed in large mouthed one gallon glass containers. Desired amountsof 'nitro-esters were added to the cutting oil emulsion. No inhibitor; was added to one 3000 ml. portion of the cutting oil emulsion which was used as a control. At the beginning of the experiment each unit was inoculated with 5 mls. of a heterogeneous bacterial culture which had grown for several years in a water-cutting oil emulsion. Aeration and mixing were obtained by bubbling compressed air through the emulsion. Water was added to each portion of the emulsion at periodic intervals in order to keep the volume of the units constant and to prevent concentration of the inhibitor by evaporation.

The following table sets out the results fromthe a-bove tests and the number of days of total bacterial inhibition when the described concentrationof the desirednitroester Example II The following is a water emulsifiable cutting oil which is adequately protected by 1000 parts per million of nitroester inhibitors.

Percent by weight Light mineral oil Oleic acid Example III The following is a stabilized steam cylinder oil which is adequately protected by 100 parts per million of 2- nitro-l-butylacetate. V

Percent by weight S.A.E. lubricating oil Oleic acid 10 Example IV The following is a core oil which is adequately pro tected by 1000 parts per million of 2-nitro-l-propylacetate.

Percent by weight Crude tall oil 25 Fuel oil 35 Tall oil ester (glycol or glycerol) 40= Example V The following is a cutting oil which is adequately protected by 1000 parts per million of nitroester inhibitors. Percent by weight Tallow 65 Paraffin wax 29 Beeswax 1.3 Oxalic acid 1.3 Potassium citrate 1.3 Urea 0.4

Now having described my invention what I claim is: 1. A stabilized liquid petroleum composition consisting essentially of a petroleum hydrocarbon lubricant and a small but suflicient amount to inhibit bacterial growth in said liquid petroleum composition of a nitroester having the following structural formula:

where R is selected from the group consisting of phenyl, methyl, ethyl, and propyl; R is selected from the group consisting of hydrogen, methyl, ethyl, and propyl; and R is selected from the group consisting of hydrogen, methyl, ethyl, and propyl.

2. A stabilized liquid petroleum composition consisting essentially of a petroleum hydrocarbon lubricant and from about 0.001 to about 2% of a nitroester having the structural formula:

where R is selected from the group consisting of p-henyl, methyl, ethyl, and propyl; R is selected from the group consisting of hydrogen, methyl, ethyl, and propyl; and

where R is selected from the group consisting of phenyl, methyl, ethyl, and propyl; R is selected from the group consisting of hydrogen, methyl, ethyl, and propyl; and R is selected from the group consisting of hydrogen, methyl, ethyl, and propyl.

References Cited in the file of this patent UNITED STATES PATENTS 2,241,246 Dickey et a1. May 6, 1941 2,427,821 Tindall Sept. 23, 1947 2,581,120 Matuszak Jan 1, 1952 2,844,538 Krug et al. July 22. 195-3 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No, 2,976,244 March 21, 1961 Edward 00 Bennett It is hereby certified that error appears in the above numbered patent requiring correction and chat the said Letters Patent should read as corrected below.

Column 2, line 3, for "Five ml, read Five 3000 ml.,

Signed and sealed this 5th day of September 19610 (SEAL) Attest:

ERNEST W. SWIDER Attesting Officer DAVID L. LADD Coissioner of Patents 

1. A STABILIZED LIQUID PETROLEUM COMPOSITION CONSISTING ESSENTIALLY OF A PETROLEUM HYDROCARBON LUBRICANT AND A SMALL BUT SUFFICENT AMOUNT TO INHIBIT BACTERIAL GROWTH IN SAID LIQUID PETROLEUM COMPOSITION OF A NITROESTER HAVING THE FOLLOWING STRUCTURAL FORMULA: 